Fuel-injecting pump for internal combustion engines



Sept. 20, 1938. H. DUNKELMANN 2,130,339

FUEL INJECTING PUMP FOR INTERNAL COMBUSTION ENGINES Filed mg. 27, 1957 Patented Sept. '20, 1938 UNITED STATES FUEL-INJECTING PUMP FOR INTERNAL COMBUSTION ENGINES Hans Dunkelmann, Kiel, Germany, assignor to Fried. Krupp Germaniawerft Aktiengesell- 'schaft, Kiel-Gaarden, Germany Application August 2'1, 1937, Serial No. 161,228 In Germany October 13, 1936 2 Claims.

My invention relates to fuel-injecting pumps for internal combustion engines comprising a differential piston freely movable in and cooperable with, two respective cylinders, the smaller piston part andcylinder supplying fuel to the working cylinder of the engine, whilst the larger piston part is acted upon by the compression pressure produced in the working cylinder of the internal combustion engine and is the driving piston for the former, this larger piston part being tightened in its cylinder by means of inwardly re-.

into the cylinder of the driving piston, easily deposit on that portion of the cylinder wall'which is located in ahead of said packing rings, that is, on the cylinder end remote from the fuel pump piston, and are coked on this wall portion. When the driving piston then glides over these coked deposits, the film of lubricating oil adhering to vide near the free end of the large piston part an outwardly resilient protective packing ring.

In order that my invention may be clearly understood and readily carried into effect, an em- I bodiment of the same is represented by way of example in the accompanying drawing which is 5 a vertical section, similar to that of the drawing accompanying the above-mentioned specification,

of a fuel-injecting pump of the type under consideration.

Referring to this drawing, a, 0. denote again 3 the casing of the fuel pump. The casing is com- I posed of several parts and has lodged in it, within corresponding cylindrical spaces, a differential piston consisting of a driving piston b of larger diameter and a fuel feeding piston c of 5 smaller diameter. The space d existing below the end face of the driving piston b communicates through a passage e and a pipe I attached thereto with the compression chamber of the working cylinder. I By 9 is denoted the pump space into which open both a passage 1 governed by the fuel inlet valve h to which leads a fuel feeding .pipe is coming from the fuel feeding pump (not shown), and a passage 1 which through the pressure pipe m leads to the fuel-injecting valve (not shown) of the working cylinder. The direction of flow of the respective agents through the pipes f, k and m is indicated by arrows.

In order to enable easy replacement of the sliding surface of the driving piston b, this surface is formed by a liner n. By 0, o are denoted inwardly resilient piston rings which are lodged in the wall of the cylinder of the piston part b and are embraced externally and laterally by superposed spacing rings :1, p of angular cross section. For the supply of the lubricant is provided a passage q which close below the piston I rings 0, 0 opens into an annular space 1' from which a' plurality of radial bores s lead up to-the sliding surface of the piston, t and u: denote flangedtubular sockets serving to supply and draw off cooling water for the cylinder of the driving piston b.

The driving piston b is extended, according to the invention, at its free end, when compared. with the corresponding piston of the above-mentioned patent, and on this extension is provided an outwardly resilient additional packing ring 1:. This packing ring is arranged in such a manner, that even in the upper dead center position of the piston b it remains below the radial bores s which feed lubricant.

Since the-packing ring 1) takes part in the reciprocating motion of the piston b, any deposition of residues of combustion penetrating from the working cylinder into the cylinder of the piston' b together with the gases of combustion is rendered impossible on the inner surface of this cylinder. Furthermore, if required, the ring 1; may be constructed as a scraper ring, that is, it may be provided with sharp edges adapted to scrape off within the range of its reciprocating motion any deposits of residues of combustion from the cylinder surface. Inthis way-also the. a drawback of contamination of the lubricant by the gases andresidues of combustion is eliminated. In addition, the packing ring 0 forms a protection against penetration of the hot gases of combustion into the lubricant feed duct. It enables, further, to dispose the feed bores s ina favorable deepest possible place and thus affords the previous conditions for a satisfactory state of lubrication of the driving piston b and its cylinder. 1

After the packing ring 11 has been flxed'to the piston b, the latter has to be inserted into its cylinder from below, since the outwardly resilient ring '0 cannot glide over the inwardly resilient packing rings 0, 0. To this end the pump casing a, a is closed atits lower end by a removable cover w, as shown, v

The provision of an outwardly resilient packing ring 1;, as described hereinbefore, near the outer end of the driving piston, that is, near 1. A fuel-injecting pump for internal combustion engines, comprising a casing, two cylindrical spaces formed therein and having diiferent sectional areas, a differential piston cooperable with said two cylindrical spaces and freely movable therein, means cooperable with the smaller piston part and cylinder for supplying fuel to and leading it from the latter to the working cylinder of the engine, means cooperable with the larger pis-'" ton part and cylinder for causing the compression pressure prevailing in' the working cylinder of the engine to act upon said larger piston part, said -"larger piston part having a smooth sliding surface and said larger cylinder having circular grooves and inwardly resilient packing rings therein cooperable with said smooth sliding surface of the larger piston part, and means, spaced from the smooth sliding surface of said larger piston and attached to the piston portion acted upon by the compression pressure prevailing in the working cylinder of the engine, for removing deposits of residues of combustion from the wall portion of said larger cylinder traversed by said smooth piston sliding surface and before the latter contacts with said wall portions.

2. A fuel-injecting pump for internal combustion engines, comprising a casing, two cylindrical spaces formed therein and having different sectional areas, a differential piston cooperable with said two cylindrical spaces and freely movable therein, means cooperable with the smaller piston part and cylinder for supplying fuel to and leading it from the latter to the working cylinder of the engine, means cooperable with the larger piston part and cylinder for causing the compression pressure prevailing in the working cylinder of the engine to act upon said larger piston part, said larger piston part having a smooth sliding surface and said larger cylinder having circular grooves and inwardly resilient packing rings therein cooperable with said smooth sliding surface of the larger piston part, and an outwardly" resilient packing ring spaced from said smooth sliding surface and disposed on said larger piston part near the end surface of the latter acted upon by the compression pressure prevailing in the working cylinder of the engine for removing deposits of residues of combustion from the wall portion of said larger cylinder traversed by said smooth piston surface and before the latter contacts with said wall portion.

HANS DUNKELMANN. 

